Paper machine saveall with de-aerator

ABSTRACT

A jet deflector for use as a saveall in a paper machine having a wide cellular roll discharging water substantially tangentially therefrom as a high speed jet extending the full width of the machine and projected into a zone of restricted access which deflector has an entry to receive the jet, a plurality of inclined, curved and twisted deflector plates, and an egg shaped flow section to receive, divert and blend the discrete entering jets into a high velocity transversely flowing stream for passage from the machine.

United States Patent Malashenko et al.

PAPER MACHINE SAVEALL WITH DE -AERATOR Inventors: Alexander Malashenko,Pointe Claire; Gordon Thomas Tidbury, Vaudreuil; Ralph James Futcher,Beaconsfield, Quebec, all of Canada Assignee: Dominion EngineeringWorks,

Limited, Lachine, Quebec, Canada Filed: Aug. 7, 1972 Appl. No.: 278,551

Foreign Application Priority Data Aug. 12, 1971 Canada 120350 U.S. Cl162/202, 162/203, 162/289,

162/300, 162/363, l62/DIG. 7 Int. Cl. D211 7/00 Field of Search 162/190,203, 205, 232,

162/274, 289, 297, 300, 301, 305, 318, 319, 321, 335, 337, 348, 351,357, 358, 359, 363, 367, 368, 369, 372, DIG. 7, 202

[56] References Cited UNITED STATES PATENTS 3,403,073 9/1968 Moran162/203 2,694,345 1 H1954 Hornbostel 162/351 Primary ExaminerS. LeonBashore Assistant Examiner-Richard V. Fisher [5 7 ABSTRACT A jetdeflector for use as a saveal] in a paper machine having a wide cellularroll discharging water substantially tangentially therefrom as a highspeed jet extending the full width of the machine and projected into azone of restricted access which deflector has an entry to receive thejet, a plurality of inclined, curved and twisted deflector plates, andan egg shaped flow section to receive, divert and blend the discreteentering jets into a high velocity transversely flowing stream forpassage from the machine.

5 Claims, 4 Drawing Figures Apr. 2, 1974- PAPER MACHINE SAVEALL WITHDE-AERATOR This invention is directed to a method of dewatering a papermachine, and to a saveall for a paper machine, and in particular to asaveall for a high speed jet to provide transverse discharge at highflow rates from a zone of limited accessibility.

Recent developments in high speed paper machines, particularly in thedevelopment of twin wire machines, having white water from the stockreleased from the periphery of a forming cylinder as a wide highvelocity jet projecting substantially parallel with and in closeproximity to one of the forming wires, have caused considerable problemsin removing the white water in satisfactory fashion from the machine.

In earlier types of machine, particularly of the socalled Fourdriniertype, water passing through the wire has fallen under gravity into aninclined saveall pan, for drainage therefrom by suitable pipes into thepit.

In twin wire machines utilizing a suction forming roll about which theforming wires are wrapped and from which roll the white water isreleased as a high velocity coherent jet, such as the paper machinetrade marked Papriformer developed by the Pulp and Paper Institute ofCanada, realization of a full width machine, in widths exceeding 200inches, leads to considerable problems in satisfactory water removal.While not being unduly direction sensitive, with reference to theorientation of the machine because of the high velocities involved,nevertheless the restricted space stemming from the geometry of themachine makes water handling a problem.

A method for disposing of a high speed jet extending the full width ofthe machine and issuing in the direction of wire travel from the surfaceof a roll, has been evolved wherein the jet is segregated into aplurality of discrete coherent jet portions of limited transversedimension; a transverse deflection component is applied in the directionof discharge; a centrifugal deflection component is applied having theinitial jet direction tangent thereto; and the resultant deflected jetportions are then blended into a high velocity smoothly flowingtransversely directed flow for passage from the machine.

In order to carry out the invention. there is provided a saveallcomprising transversely elongated walls defining a jet receivingaperture extending the full width of the machine to be dewatered,thewalls being spaced apart a sufficient distance to receive the fulldepth of the jet and extending initially in substantially the samedirection as the incident jet; a curved blocking portion of one of thewalls extending across the thickness of the path of the jet indeflecting relation therewith to provide a centrifugal component ofmotion to an entering 1 jet; a plurality of deflector plates spacedacross the width of the jet and sloping towards the curved wall portionin the direction of jet transverse discharge divide the jet intodiscrete jet portions; and a transversely extending flow passagereceiving the deflected high ve locity jet portions in blending flowtherethrough.

In dividing up the machine width into a plurality of adjoining zones thetransverse spacing of the deflector plates in the cross machinedirection is selected so that the interval is sufficiently small toensure effective transverse deflection across the full width of eachzone, between adjacent plates. The transverse inclination or angle ofoutward slope of the deflector plates is limited to avoid choking in thetriangular root portions thus formed. An angle of inclination of about35 between the edges of the jet entry has been found to be effective.

One effective curvature of the deflector plates has been found to besubstantially cylindrical, the plates being made from steel sheet andgiven a slight warp to progressively increase the transverse deflectionat the centrifugally outer edge thereof.

It has been found that a saveall having a substantially constant crosssection that is transversely non-varying is effective, having an eggshaped recovery section in which the machine discharge takes place inthe cross machine direction.

The achievement of effective transverse discharge by way of a catchallof limited depth, relative to the jet inlet dimension is of particularsignificance in relation to the space problems encountered in a machineof this type.

A particular result provided by the subject catchall is the centrifugaldeaeration of the white water which may be achieved. In the operation ofa paper machine of the type described, the white water, after passagethrough a forming wire, is initially held in the foraminous shell of theforming roll and subsequently released therefrom under centrifugalforce, at a velocity approaching that of the high speed forming wire.The

jet thus formed, which projects a distance up to as much as 4 feetthrough the air into the saveall is highly turbulent and aerated.

As a consequence of the centrifugal deflection component applied to thejet in the saveall, and also as a result of the arcuate transversedeflection of the component jets to the back of the machine, there is aconsiderable degree of air separation, tending to form an air core tothe white water flowing transversely through the saveall. The provisionof an air collection chamber on an outer wall of the catchall, havingone or more apertures connecting with at least some of the air chimneyswhich bound the discontinuities of the white water flow, permitsadequate ventilation of the interior of the catchall. This leads toimproved qualityby deaeration of the white water before returning it tothe paper making process.

Certain embodiments of the invention are described with reference to theattached drawings, wherein FIG. 1 is a general view of a catchallaccording to the present invention;

FIG. 2 is a cross sectional view at 2-2 of FIG. 1; I

FIG. 3 is a front or head-on sectional view at 3-3 of FIG. 2; and

FIG. 4 is a plan view of a blade member of the catchall.

Referring first to FIGS. 1 and 2, the catchall 10 has a casing 12 ofwrapped section for extending transversely across the machine. Wallportions 14, 16 of the casing 12 define an entrance mouth of rectangularcross section having a plurality of deflector blades 18 spacedthereacross. The blades 18 at the mouth (see FIG. 3) are inclined fromtheir top edge adjoining the surface 14, being twisted substantiallyuniformly along their respective lengths to exert a transversedeflection to incoming liquid. The form and arrangement of the blades18, as secured in the casing 12, thus provides separation of theinflowing jet into discrete portions that are deflected downwardly bythe combined form of the blades 18 and the downward curve of the casing12. The curve or transverse displacement of the blades 18 producesregulated transverse deflection of the discrete jets, while the twist ofthe blades 18 produces a wrap-over effect complementary to the downwardcurve of the back inner surface 20 of the casing 12.

In operation, an incoming aerated jet is deflected downwardly andtransversely into a contained high velocity liquid flow. The effect ofthis controlled deflection is to provide separation of air, from theentrapped air entering with the white water jet into the catchall. Theentrapped air tends to separate by centrifugal action, and is bled-offby way of an air bleed aperture 22 that connects the interior of casing12 with an air trunking 24 attached to the top wall of casing 12. Directentry of liquid into the aperture 22 is precluded by the fact that theaperture or slot 22 opens in a downstream-facing direction, adjacent theincoming jet.

A passage bounded by walls 29 or a series of pipes equivalent theretoconnect the air trunking 24 with a suitable vacuum header 28.

A suitable downcomer pipe (not shown) connected with the outlet end ofthe catchall permits transference of the white water to the pit orholding tank.

In the case of a machine having a catchall according to this inventionextending the full width of the machine, it is possible to retrieve thewhite water solely from the rear of the machine, thus simplifying pipingprovisions and leaving the front or aisle side of the machineunencumbered, to facilitate wire changes.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A method of dewatering a high speed paper machine, wherein a wide jetof water of limited depth and extending laterally in the cross-machinedirection is projected through the air as a substantially planar jet athigh velocity in a direction normal to said crossmachine direction,comprising the steps of: directing the jet towards a save-all having apair of opposed wall portions defining lips of an inlet mouth, whichlips receive the jet therebetween, said mouth being surrounded by acurved casing, separating the jet into a plurality of discrete jetportions by a plurality of parallel deflection plates spaced across themouth, said deflector plates being l) curved along their respectivelengths to produce a substantially uniform transverse deflection of thediscrete jet portions from the mouth to the casing, and (2) twistedalong their respective lengths to produce a wrap-over motion of thediscrete jet portions, which motion being complimentary to the curve ofthe casing, whereby the curved and twisted parallel deflection platespromote centrifugal separation of the air from the water in said casingand promote flow displacement of the water through the casing in thecross-machine direction, and combining the respectively centrifugedwater flows in the casing while substantially maintaining separation ofthe entrained air from the water flows during the discharge of the waterin the cross-machine direction.

2. The method according to claim 1 including the step of removing saidentrained air by suction.

3. A saveall for use in the dewatering of a high speed paper machinewherein a wide jet of water having a limited depth and extendinglaterally in the crossmachine direction is projected through the air asa substantially planar jet at high velocity in a direction normal tosaid cross-machine direction, said saveall comprising an inlet having apair of opposed wall portions defining lips of an inlet mouth, whichlips receive the jet therebetween, a curved casing having a portionadjoining said mouth but displaced therefrom out of the plane of thejet, and a plurality of parallel deflection plates spaced across themouth to separate the jet into discrete jet portions, said deflectorplates being (1) curved along their respective lengths to produce asubstantially uniform transverse deflection of the discrete jet portionsfrom said mouth to said casing, and (2) twisted along their respectivelengths to produce a wrap-over motion of the discrete jet portions,which motion being complimentary to the curve of the casing, whereby thecurved and twisted parallel deflection plates promote centrifugalseparation of the air from the water in said casing and promote flowdisplacement of the water through the casing in the cross-machinedirection.

4. The saveall as claimed in claim 3 having air removal means connectedthereto in shrouded relation with the interior of said casing portion,to substantially preclude direct entry of water therein.

5. The saveall as claimed in claim 3 wherein said parallel plates arespaced transversely across said mouth, each being inclined to said wallportions to define an angle of about 35 with the plane of said jet.

2. The method according to claim 1 including the step of removing saidentrained air by suction.
 3. A saveall for use in the dewatering of ahigh speed paper machine wherein a wide jet of water having a limiteddepth and extending laterally in the crossmachine direction is projectedthrough the air as a substantially planar jet at high velocity in adirection normal to said cross-machine direction, said saveallcomprising an inlet having a pair of opposed wall portions defining lipsof an inlet mouth, which lips receive the jet therebetween, a curvedcasing having a portion adjoining said mouth but displaced therefrom outof the plane of the jet, and a plurality of parallel deflection platesspaced across the mouth to separate the jet into discrete jet portions,said deflector plates being (1) curved along their respective lengths toproduce a substantially uniform transverse deFlection of the discretejet portions from said mouth to said casing, and (2) twisted along theirrespective lengths to produce a wrap-over motion of the discrete jetportions, which motion being complimentary to the curve of the casing,whereby the curved and twisted parallel deflection plates promotecentrifugal separation of the air from the water in said casing andpromote flow displacement of the water through the casing in thecross-machine direction.
 4. The saveall as claimed in claim 3 having airremoval means connected thereto in shrouded relation with the interiorof said casing portion, to substantially preclude direct entry of watertherein.
 5. The saveall as claimed in claim 3 wherein said parallelplates are spaced transversely across said mouth, each being inclined tosaid wall portions to define an angle of about 35* with the plane ofsaid jet.